JPS6052171B2 - Polyolefin composition with good salt water resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyolefin compositions that exhibit excellent salt water resistance when laminated to metal.

BACKGROUND ART Conventionally, in order to protect the surface of water-conducting steel pipes and the like from corrosion, methods of coating the metal surface with a corrosion-resistant resin such as polyolefin have been studied. Polyolefins do not have polarity on their surfaces, so they cannot adhere firmly to metal surfaces.
It is not possible to apply a coating that can withstand practical use. In order to solve this drawback, measures have been taken to introduce polar groups, such as carboxyl groups or carboxylic acid anhydride groups, into the resin. By this measure, it may be possible to firmly adhere the polyolefin to the metal surface, but water resistance, especially salt water resistance, which is an even more important practical requirement, does not reach a sufficient level. Therefore, in order to solve this drawback, we added a material on the metal surface that has affinity for both metal and polyolefin. . However, this primer treatment results in an additional process, resulting in a decrease in productivity and an increase in product price. The inventors of the present invention have arrived at the present invention as a result of intensive studies aimed at creating a polyolefin composition that exhibits sufficient salt water resistance without applying any treatment such as a primer to the metal surface.

The present invention comprises (a) 10 parts of a polyolefin containing a group derived from a carboxyl group (however, excluding the case where all the groups are alkoxycarbonyl groups), (b) 1 part of a chlorinated synthetic rubber, 3 The present invention relates to a polyolefin composition having good salt water resistance and comprising a heel portion and (c) 0.05 to 5 parts by weight of a halogen-containing compound of a divalent metal.

A polyolefin (hereinafter referred to as a hydrophilic polyolefin) containing a group derived from a carboxyl group, which is the component (a) (excluding cases in which all the groups are alkoxycarbonyl groups), is a polyolefin containing, for example, a polyolefin in an aqueous dispersion state. , obtained by contacting with oxygen or an oxygen-containing gas in an organic solvent solution or in the molten state (
i) a polyolefin oxide and (ii) a modified polyolefin grafted with a compound selected from unsaturated aliphatic carboxylic acids or derivatives thereof (hereinafter referred to as an acid compound), (ii) a copolymer of an olefin and an acid compound; itself or (Iv) 1 of (1) to (Iiii) above
Any of the above-mentioned compositions with other polyolefins and inns may be used.

When this hydrophilic polyolefin is used alone, its acid value is usually 0.5 to 150, preferably 5 to 140 based on monovalent carboxylic acid units, and preferably 5 to 140 based on divalent carboxylic acid or its anhydride units. is 0.5 to 3
Select 0. When used in the form of a composition with other polyolefins, the composition may be prepared so that the acid value of the composition is usually 0-3 to 1, preferably 0.5 to 10. . The polyolefin composition of the present invention must contain, in addition to the hydrophilic polyolefin, a chlorine-containing synthetic rubber or a chlorine-containing synthetic rubber and a halogen-containing compound of a divalent metal. Shows water-based properties.

To prepare the composition of the present invention, 1 to 3 parts by weight of chlorine-containing synthetic rubber, preferably 5 to 15 parts by weight, and usually 0.0 parts by weight of a halogen-containing divalent metal are added to 100 parts by weight of the hydrophilic polyolefin. 05 to 5 parts by weight, preferably 0.1 to 1.0 parts by weight. Normal salt water resistance is sufficiently achieved by using a dam.

In the present invention, compounds selected from unsaturated aliphatic carboxylic acids or derivatives thereof (acidic compounds) that may be used to produce hydrophilic polyolefins include free acids, their acid anhydrides, acid halides, and acid compounds. Amides, imides, partial esters, salts, and partial hydrolysates thereof) may coexist within the same molecule.
For example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, 3-cyclohexenecarboxylic acid, 4-cyclohexenedicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, Examples include oil chloride, maleimide, monomethyl maleate, sodium acrylate, calcium acrylate, zinc acrylate, potassium methacrylate, calcium methacrylate, zinc methacrylate, dipotassium maleate, zinc maleate, and partial hydrolysates thereof. In the present invention, the polyolefin refers to a 1-carbon atom containing usually 1 to 1 carbon atom, such as ethylene, pyrene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and 1-decene. Homopolymers and copolymers of olefins, such as polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymers, ethylene-butene copolymers, propylene-1-butene copolymers, Ethylene-4-methyl-1-pentene copolymers, 4-methyl-1-pentene-1-decene copolymers, copolymers of the above-mentioned 1-olefins with small amounts of diolefins, such as ethylene-butadiene copolymers and propylene-butadiene copolymers. The composition may be a combination of two or more selected from single polymers, various homopolymers, and various copolymers thereof, and may be crystalline or amorphous.

Wax-like materials are not suitable for adhesive evaluation based on tensile strength, but sufficient effects are recognized by other evaluation methods. Polyethylene, which is one of the typical crystalline polyolefins among these polyolefins, has, for example, an intrinsic viscosity [η] of a decalin solution at 135° C., usually 0.5 to 5.0, preferably 0.7 to 3. 0. ．． X-ray crystallinity 60-85%, density 0.90-0.97y/
Mll is preferably in the range of 0.92 to 0.96y/TLl. This polyethylene may be a copolymer containing 1-olefin units such as propylene units, 1-butene units, butadiene units, etc. in addition to ethylene units. Further, as polypropylene, for example, [η] in 135 mouths C of decalin solution is usually 0.5 to 10, preferably 1.0 to 4.0. X-ray crystallinity usually 50 to 60%, density 0.90 to 0.92y
For example, in the case of a copolymer with ethylene, the ethylene unit content is usually 8 m01% or less.

Examples of the chlorine-containing synthetic rubber to be blended into the polyolefin composition of the present invention include chloroprene rubber, chlorinated butyl rubber, chlorosulfonated polyethylene, and epichlorohydrin rubber. Chlorine-containing compounds of divalent metals are a comprehensive concept, and include not only dichlorides but also their hydrates, oxychlorides, chlorides, and hydroxides. Divalent metals and chlorine, such as complexes and complexes with substances, hydrates thereof, complexes and complexes with chlorides and oxides, hydrates, double chlorides and complex chlorides, hydrates thereof, etc. Refers to a compound that contains a bond with.

Preferred are dichlorides and their hydrates. The mechanism by which these chlorine compounds contribute to improving salt water resistance is not clear, but when they are blended with components (a) and (b) and melt-molded, they generate components such as hydrogen chloride, which can cause the metal surface to deteriorate. It is presumed that suitable processing will be applied to the

Divalent metals include, for example, metals in group 2 of the periodic table such as magnesium, calcium, barium, strontium, and zinc; metals in group 4 such as tin (2017) and lead; metals in group 7 such as manganese;
Group 8 metals such as iron (), cobalt (), nickel (), etc. can be mentioned. Among these, magnesium, calcium, zinc, and iron () are preferred. The composition of the present invention is prepared by mixing a hydrophilic polyolefin, finely divided chlorine-containing synthetic rubber, and a halogen-containing divalent metal compound in a tumbler mixer, V-type blender, pen shell mixer, etc. mixer,
It is preferable to use a method of kneading using two rolls, an extruder, a kneader, or the like.

The composition of the present invention may further contain small amounts of heat stabilizers, weather stabilizers, hydrochloric acid absorbers, lubricants, fillers, pigments, and the like.

By using the polyolefin composition of the present invention as described above, a metal can be coated with a polyolefin having excellent adhesion and particularly excellent salt water resistance.

Therefore, conventionally, for applications requiring salt water resistance, the metal surface was primed and then coated with polyolefin, but as a result of the present invention, the process can be simplified by omitting the primer treatment. There are advantages. The composition of the present invention can be applied, for example, to anti-rust coatings on the inner and outer surfaces of steel pipes for water and sewage, to anti-rust coatings on metal members used in corrosive atmospheres such as manholes and sewage, and to anti-rust coatings on metal materials that are immersed in seawater. Suitable for anti-rust coating of metal materials used under harsh conditions.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded. Comparative Examples 1 to 3 High density polyethylene (melt index (190°C)
14, density 0.965y/CTl) with maleic anhydride 2
5 parts by weight of ethylene-propylene copolymer (melt index 4, density 0.92)
5y/CTl) and 95 parts by weight of chloroprene rubber (trade name: Neoprene WBL, manufactured by Showa Neoprene Co., Ltd., Mu[
The mixtures were mixed using a tumbler mixer in the proportions shown in Table 1, and then granulated using an extruder at 190°C to obtain a polyolefin composition.

This composition was placed on a steel plate (thickness 170F7) whose surface had been hub-polished and degreased with acetone, and the composition was pressed into a laminated sheet (each layer had a thickness of 1 Moe) was created.
This laminated sheet was tested for initial adhesive strength and salt water resistance using the following method. (1) Measurement of initial adhesive strength A test piece with a width of 20 Tr0n was cut from the laminate that had been molded for a while, and a peel angle of 18
Peel strength (K
g/Cm) was measured.

(2) Salt water resistance test A test piece with a width of 2-2 was cut from the laminate, and the temperature was 3% by weight.
The width of natural peeling from one edge of the test piece after 1 and 3 days of immersion in saline solution at a temperature of 60°C is indicated by a gourd.

Furthermore, the adhesive strength of the above test piece was measured in the same manner as the initial adhesive strength, and the change in adhesive strength over time was observed.

The results of Comparative Examples 1 to 3 are shown in Table 1. Comparative Example 4 Comparative Example 1 except that the formulation does not contain chloroprene
I went in the same way.

The results are shown in Table 1. It can be seen that if chloroprene rubber is not blended, the peeling rate in salt water exceeds 25 wn/hour, making it unusable. Comparative Example 5 A test piece was prepared in the same manner as in Comparative Example 1 except that the maleic anhydride-grafted high-density polyethylene was not mixed, but this polyolefin composition did not adhere to the metal plate at all.

Examples 1 and 2 High density polyethylene (melt index (190°C)
14, density 0.965y/CTl) with maleic anhydride 2
5 parts by weight of ethylene-propylene copolymer (melt index 4, density 0.925
y/d) 95 parts by weight, chloroprene rubber (trade name Neoprene WB) W parts by weight, and 0 metal chlorides shown in Table 1.
．． The same procedure as Comparative Example 1 was conducted except that 3 parts by weight of the composition was used.

Claims (1)

[Claims] 1 (a) 100 parts by weight of a polyolefin containing a group derived from a carboxyl group (excluding when all the groups are alkoxycarbonyl groups), (b) 1 to 30 parts by weight of chlorine-containing synthetic rubber, and (c) ) A polyolefin composition having good salt water resistance and comprising 0.05 to 5 parts by weight of a divalent metal halogen-containing compound.